I had the same call lawsuit by the IRS went to IRS.gov they never call you will receive letter. Checked with lawyer they said the same you will not get a call you will get a letter.
Yep, just happened to my 95 year old mom this morning. 206-488-5864. Disgusting! Preying on people. We pay our taxes on time, every year, and to go after someone so vulnerable. Shameful!